UNC Researchers Convert Solar Energy Into Fuel

The new system generates fuel by using the sun's energy to split water into its component parts - storing hydrogen, releasing oxygen.

Credit Yan Liang / Energy Frontier Research Center UNC-Chapel Hill

The Frontier Research Center at UNC-Chapel Hill has built a system that converts solar energy into fuel, so power can be used even after the sun sets. The US Department of Energy is funding the research.

Instead of storing solar electricity in an expensive battery, researchers use the sun's energy to separate water into hydrogen and oxygen. Two of the Center's papers about the process were recently published in the Proceedings of the National Academy of Sciences.

Chemistry Professor Tom Meyer says the system uses solar power during the day to cheaply separate hydrogen and oxygen from water. The elements can then be stored separately and burned for power. Meyer says power utilities already have infrastructure for that last part:

See, that's the beauty of it, I think. With this, you can plug into existing engineering, existing technologies. People know how to generate hydrogen. They know how store it. They know how to use it to extract energy in a power plant. So that's all done. You know, all we want to do is find a way to give it to them in a relatively inexpensive way using the sun.

Meyer says the method could be useful and cost-effective for power utilities someday:

This is a basic research project that's knocking on the door to become a technology. I think the principles are established and it's really important, but the efficiency of the devices that we have are very low. That is, ‘Here's all the sun's energy. How much do you actually use in a useful way?’ And the answer's about one percent.

That means only one percent of the solar power that reaches the device is currently used to convert water into fuel. Meyer says the process wouldn't be viable on a commercial scale until technology reached about 10 percent efficiency, which could take a few decades.

He says his team is also looking at how carbon dioxide could be split into its basic elements for fuel, as well.